Okey dokey, well this is a topic I have seen many times but rarely from people actually versed in all the characters. So I thought I'd give my ten cents.

This is a straight fight, no plot-induced stupidity on either character's part. If they have a power they use it and use it right. As a baseline, I am using an Annihilation Wave/Post-Infinity War Thanos who is killable. The Thanos Quest version was basically indestructable and immortal, and I'm not really sure of the limits of his abilities as he was pretty much only used against god-like beings with undefined power levels.

1. v. Golden Age Superman
   Thanos would vaporise GA Superman with an energy blast. Thanos 100/100
2. v. Silver Age Superman
   I don't know that Thanos could actually hurt Silver Age Superman. Though Thanos' intellect usually gives him an edge in the few people that out-class him he doesn't have jack on Silver Age Superman's intelligence. SA Superman 99/100
3. v. Byrne-era Superman
   Byrne's Superman barely survived a nuclear explosion, and it wasn't even a large one. Thanos pops him like a grape. Thanos 95/100.
4. v. late Post-Crisis Superman
   While Superman amped up his speed, strength and brains by leaps and bounds during this period he was no match for the Titan in either intellect or physical strength. His speed advantage is negated, because Thanos can clearly move at near light-speed if he sees fit and that was the limit of LPC Superman's "local" velocity (his TTK was warping space interstellar, useless for close-combat). Thanos 80/100.
5. v. New 52 Superman
   It is hard to say the limits of this Superman's power, but based on feats (and who has been able to hurt him) I would give it to Thanos 90/100.
6. v. Early Supreme (Rob Liefeld)
   Supreme is a hell of a fighter and dreadfully powerful in his initial incarnation, about as powerful as New Earth Superman plus a huge amount of adaptability/flux. I'd say Thanos 70/100, based on brains and raw power.
7. v. Later Supreme (Rob Liefeld)
   This was a much-reduced character, and Thanos takes this 90/100.
8. v. Supreme (Alan Moore)
   A less-arbitrary version of Silver Age Superman in many respects, I would give this to Supreme 90/100.
9. v. Mr. Majestic (Wildstorm/Image)
   Majestic showed great control over his energy blasts, virtually unlimited physical strength and awesome intelligence and super-speed. I would say the Titan is noticeably smarter, but not enough to enable him to Deus Ex Machina defeat Majestic. 50/100 for both fighters, a solid match-up.
10. v. Miracleman/Marvelman (Alan Moore)
    This incarnation of MM was seemingly indestructable, but as Kid Marvelman showed their powers suffer from a fatal weakness in that it is a body changing and force-field based ability. Thanos stomps, 100/100.
11. v. Miracleman/Marvelman (Neil Gaiman)
    This version of the character had incredible abilities, such as bestowing powers and talents on others. An upgrade from Alan Moore's I still don't see the intelligence or experience with Thanos-level threats. Thanos 90/100.
12. v. Gladiator (Marvel)
    Gladiator is a very powerful guy, but the source and limits of his powers have never visibly exceeded, really, Byrne-era Superman in most of his appearances. He lacks the brains to take on the Titan, in any case (not that he's dumb, but come on, Reed Richards is dumb to Thanos).
    Thanos, 100/100
13. v. Count Nefaria Fully Upgraded (Marvel)
    Theoretically, if in-story claims can be trusted, Count Nefaria would become more and more powerful almost without limit over time. This means he could eventually beat Thanos with one punch. Of course, the same is true of the Hulk - and that ain't happenin'. Also, Count Nefaria was one dumb-ass super-scientist, so Thanos 99/100.
14. v. Sentry
    I'll try to control my annoyance at what might be the worst Superman pastiche ever to objectively evaluate him. Not impressed. Very weird energy manipulation and shapechange abilities, but he didn't put up nearly the fight Thanos has (and, frankly, Thanos only loses to himself). He was also a crackhead lunatic who didn't fight effectively because he spent most of the time freaking out and talking to himself.
    Thanos 90/100.
15. v. Captain Marvel (DC)
    This is basically equivalent to New Earth Superman. Thanos is a sorcerer of some skill himself, and is not vulnerable to magic. And Thanos is smarter than Solomon. So, Thanos 80/100
16. v. Black Adam
    I think Teth-Adam is a better fighter and a much more experienced god-man than Captain Marvel. He is also more intelligent, and fights to kill most of the time.
    Thanos 70/100.